content: /* Copyright (C) 2016-2018 Alibaba Group Holding Limited
  
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
  
      http://www.apache.org/licenses/LICENSE-2.0
  
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  ==============================================================================*/
  
  // Protocol Buffers - Google's data interchange format
  // Copyright 2008 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  package com.google.protobuf.util;
  
  import static com.google.common.base.Preconditions.checkArgument;
  
  import com.google.common.base.CaseFormat;
  import com.google.common.base.Joiner;
  import com.google.common.base.Splitter;
  import com.google.common.primitives.Ints;
  import com.google.protobuf.Descriptors.Descriptor;
  import com.google.protobuf.Descriptors.FieldDescriptor;
  import com.google.protobuf.FieldMask;
  import com.google.protobuf.Internal;
  import com.google.protobuf.Message;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  
  /**
   * Utility helper functions to work with {@link com.google.protobuf.FieldMask}.
   */
  public class FieldMaskUtil {
    private static final String FIELD_PATH_SEPARATOR = ",";
    private static final String FIELD_PATH_SEPARATOR_REGEX = ",";
    private static final String FIELD_SEPARATOR_REGEX = "\\.";
  
    private FieldMaskUtil() {}
  
    /**
     * Converts a FieldMask to a string.
     */
    public static String toString(FieldMask fieldMask) {
      // TODO(xiaofeng): Consider using com.google.common.base.Joiner here instead.
      StringBuilder result = new StringBuilder();
      boolean first = true;
      for (String value : fieldMask.getPathsList()) {
        if (value.isEmpty()) {
          // Ignore empty paths.
          continue;
        }
        if (first) {
          first = false;
        } else {
          result.append(FIELD_PATH_SEPARATOR);
        }
        result.append(value);
      }
      return result.toString();
    }
  
    /**
     * Parses from a string to a FieldMask.
     */
    public static FieldMask fromString(String value) {
      // TODO(xiaofeng): Consider using com.google.common.base.Splitter here instead.
      return fromStringList(null, Arrays.asList(value.split(FIELD_PATH_SEPARATOR_REGEX)));
    }
  
    /**
     * Parses from a string to a FieldMask and validates all field paths.
     *
     * @throws IllegalArgumentException if any of the field path is invalid.
     */
    public static FieldMask fromString(Class<? extends Message> type, String value) {
      // TODO(xiaofeng): Consider using com.google.common.base.Splitter here instead.
      return fromStringList(type, Arrays.asList(value.split(FIELD_PATH_SEPARATOR_REGEX)));
    }
  
    /**
     * Constructs a FieldMask for a list of field paths in a certain type.
     *
     * @throws IllegalArgumentException if any of the field path is not valid.
     */
    // TODO(xiaofeng): Consider renaming fromStrings()
    public static FieldMask fromStringList(Class<? extends Message> type, Iterable<String> paths) {
      FieldMask.Builder builder = FieldMask.newBuilder();
      for (String path : paths) {
        if (path.isEmpty()) {
          // Ignore empty field paths.
          continue;
        }
        if (type != null && !isValid(type, path)) {
          throw new IllegalArgumentException(path + " is not a valid path for " + type);
        }
        builder.addPaths(path);
      }
      return builder.build();
    }
  
    /**
     * Constructs a FieldMask from the passed field numbers.
     *
     * @throws IllegalArgumentException if any of the fields are invalid for the message.
     */
    public static FieldMask fromFieldNumbers(Class<? extends Message> type, int... fieldNumbers) {
      return fromFieldNumbers(type, Ints.asList(fieldNumbers));
    }
  
    /**
     * Constructs a FieldMask from the passed field numbers.
     *
     * @throws IllegalArgumentException if any of the fields are invalid for the message.
     */
    public static FieldMask fromFieldNumbers(
        Class<? extends Message> type, Iterable<Integer> fieldNumbers) {
      Descriptor descriptor = Internal.getDefaultInstance(type).getDescriptorForType();
  
      FieldMask.Builder builder = FieldMask.newBuilder();
      for (Integer fieldNumber : fieldNumbers) {
        FieldDescriptor field = descriptor.findFieldByNumber(fieldNumber);
        checkArgument(
            field != null,
            String.format("%s is not a valid field number for %s.", fieldNumber, type));
        builder.addPaths(field.getName());
      }
      return builder.build();
    }
  
    /**
     * Converts a field mask to a Proto3 JSON string, that is converting from snake case to camel
     * case and joining all paths into one string with commas.
     */
    public static String toJsonString(FieldMask fieldMask) {
      List<String> paths = new ArrayList<String>(fieldMask.getPathsCount());
      for (String path : fieldMask.getPathsList()) {
        if (path.isEmpty()) {
          continue;
        }
        paths.add(CaseFormat.LOWER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, path));
      }
      return Joiner.on(FIELD_PATH_SEPARATOR).join(paths);
    }
  
    /**
     * Converts a field mask from a Proto3 JSON string, that is splitting the paths along commas and
     * converting from camel case to snake case.
     */
    public static FieldMask fromJsonString(String value) {
      Iterable<String> paths = Splitter.on(FIELD_PATH_SEPARATOR).split(value);
      FieldMask.Builder builder = FieldMask.newBuilder();
      for (String path : paths) {
        if (path.isEmpty()) {
          continue;
        }
        builder.addPaths(CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, path));
      }
      return builder.build();
    }
  
    /**
     * Checks whether paths in a given fields mask are valid.
     */
    public static boolean isValid(Class<? extends Message> type, FieldMask fieldMask) {
      Descriptor descriptor = Internal.getDefaultInstance(type).getDescriptorForType();
  
      return isValid(descriptor, fieldMask);
    }
  
    /**
     * Checks whether paths in a given fields mask are valid.
     */
    public static boolean isValid(Descriptor descriptor, FieldMask fieldMask) {
      for (String path : fieldMask.getPathsList()) {
        if (!isValid(descriptor, path)) {
          return false;
        }
      }
      return true;
    }
  
    /**
     * Checks whether a given field path is valid.
     */
    public static boolean isValid(Class<? extends Message> type, String path) {
      Descriptor descriptor = Internal.getDefaultInstance(type).getDescriptorForType();
  
      return isValid(descriptor, path);
    }
  
    /**
     * Checks whether paths in a given fields mask are valid.
     */
    public static boolean isValid(Descriptor descriptor, String path) {
      String[] parts = path.split(FIELD_SEPARATOR_REGEX);
      if (parts.length == 0) {
        return false;
      }
      for (String name : parts) {
        if (descriptor == null) {
          return false;
        }
        FieldDescriptor field = descriptor.findFieldByName(name);
        if (field == null) {
          return false;
        }
        if (!field.isRepeated() && field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
          descriptor = field.getMessageType();
        } else {
          descriptor = null;
        }
      }
      return true;
    }
  
    /**
     * Converts a FieldMask to its canonical form. In the canonical form of a
     * FieldMask, all field paths are sorted alphabetically and redundant field
     * paths are moved.
     */
    public static FieldMask normalize(FieldMask mask) {
      return new FieldMaskTree(mask).toFieldMask();
    }
  
    /**
     * Creates a union of two or more FieldMasks.
     */
    public static FieldMask union(
        FieldMask firstMask, FieldMask secondMask, FieldMask... otherMasks) {
      FieldMaskTree maskTree = new FieldMaskTree(firstMask).mergeFromFieldMask(secondMask);
      for (FieldMask mask : otherMasks) {
        maskTree.mergeFromFieldMask(mask);
      }
      return maskTree.toFieldMask();
    }
  
    /**
     * Calculates the intersection of two FieldMasks.
     */
    public static FieldMask intersection(FieldMask mask1, FieldMask mask2) {
      FieldMaskTree tree = new FieldMaskTree(mask1);
      FieldMaskTree result = new FieldMaskTree();
      for (String path : mask2.getPathsList()) {
        tree.intersectFieldPath(path, result);
      }
      return result.toFieldMask();
    }
  
    /**
     * Options to customize merging behavior.
     */
    public static final class MergeOptions {
      private boolean replaceMessageFields = false;
      private boolean replaceRepeatedFields = false;
      // TODO(b/28277137): change the default behavior to always replace primitive fields after
      // fixing all failing TAP tests.
      private boolean replacePrimitiveFields = false;
  
      /**
       * Whether to replace message fields (i.e., discard existing content in
       * destination message fields) when merging.
       * Default behavior is to merge the source message field into the
       * destination message field.
       */
      public boolean replaceMessageFields() {
        return replaceMessageFields;
      }
  
      /**
       * Whether to replace repeated fields (i.e., discard existing content in
       * destination repeated fields) when merging.
       * Default behavior is to append elements from source repeated field to the
       * destination repeated field.
       */
      public boolean replaceRepeatedFields() {
        return replaceRepeatedFields;
      }
  
      /**
       * Whether to replace primitive (non-repeated and non-message) fields in
       * destination message fields with the source primitive fields (i.e., if the
       * field is set in the source, the value is copied to the
       * destination; if the field is unset in the source, the field is cleared
       * from the destination) when merging.
       *
       * <p>Default behavior is to always set the value of the source primitive
       * field to the destination primitive field, and if the source field is
       * unset, the default value of the source field is copied to the
       * destination.
       */
      public boolean replacePrimitiveFields() {
        return replacePrimitiveFields;
      }
  
      public MergeOptions setReplaceMessageFields(boolean value) {
        replaceMessageFields = value;
        return this;
      }
  
      public MergeOptions setReplaceRepeatedFields(boolean value) {
        replaceRepeatedFields = value;
        return this;
      }
  
      public MergeOptions setReplacePrimitiveFields(boolean value) {
        replacePrimitiveFields = value;
        return this;
      }
    }
  
    /**
     * Merges fields specified by a FieldMask from one message to another with the
     * specified merge options.
     */
    public static void merge(
        FieldMask mask, Message source, Message.Builder destination, MergeOptions options) {
      new FieldMaskTree(mask).merge(source, destination, options);
    }
  
    /**
     * Merges fields specified by a FieldMask from one message to another.
     */
    public static void merge(FieldMask mask, Message source, Message.Builder destination) {
      merge(mask, source, destination, new MergeOptions());
    }
  }
  